In the papermaking and converting industries, scrap trim waste is continuously produced by trimming or die cutting equipment, and the trim waste is commonly carried away or transferred by a venturi inducer system of the general type, for example, disclosed in U.S. Pat. No. 5,069,582. The trim waste may be in the form of a continuous matrix or skeleton of pressure sensitive adhesive which originates from a label die cutting operation and is formed into a rope-like continuous supply, for example, as disclosed in U.S. patent application Ser. No. 09/657,244, filed Sep. 7, 2000 by the Assignee of the present invention.
As disclosed in the above-mentioned ""582 patent, a continuous supply of scrap or trim material is directed into a suction device or venturi inducer having a cylindrical suction duct which connects with a cylindrical intake duct of the inducer. A generally cylindrical housing surrounds the intake duct and defines therebetween an annular air chamber which receives pressurized air from an electric motor driven blower. The housing has a frusto-conical or tapered end portion which cooperates with the inner end of the intake duct to define an annular nozzle gap or opening through which the pressurized air flows to induce, by a venturi action, a suction within the intake duct for pulling the continuous supply of material into the duct. The air flowing through the nozzle opening is directed through a throat for blowing the material into an outake or outlet duct which tapers slightly outwardly in diameter and connects with a cylindrical material transfer duct.
The size of the motor driven blower is selected according to the size of the inducer and the particular trim material to be transferred by the inducer and the velocity at which the trim material is produced. Usually, the air blower is selected with an electric motor having a higher horsepower rating than is actually needed since pressure blowers are available in only limited number of sizes. A damper valve is commonly used in the outlet of the pressure blower to provide for adjusting the air flow rate through the nozzle opening to select a sufficient flow rate to carry the trim material through the ducts. For example, while only twenty-six horsepower may be necessary to produce the necessary air flow through the nozzle opening to transfer the material, it is necessary to select a blower having a thirty horsepower electric motor. A damper is then used to reduce the blower output to twenty-six horsepower. The manufacturer of the blowers commonly provide charts which show the performance of the blowers in terms of horsepower versus cubic feet per minute of air flow.
After a venturi inducer system has been installed in a duct system for conveying a particular waste or trim material, it has been found highly desirable to provide for adjusting the area of the annular nozzle opening within the inducer in order to obtain the optimum air flow rate for transferring the material while minimizing the horsepower required from the blower motor.
The present invention is directed to an improved venturi inducer system of the general type described above and which incorporates means for externally and infinitely adjusting the inner end of the intake duct axially after the system has been installed. This adjustment thus provides for precisely adjusting the annular area of the nozzle opening for selecting the air flow rate and the velocity of air flowing through the nozzle opening according to the mass and speed of trim material being continuously supplied in order to avoid plugging of the ducts. The inducer system of the invention also provides for minimizing the electrical power required by the blower motor and thus eliminates the need for oversizing the blower motor. The inducer system of the invention further provides for using one blower with a plurality of at least two inducers of the same size or different sizes since the nozzle opening of each inducer may be individually adjusted. This results in a lower investment cost for equipment used in the system.
In accordance with one embodiment of the invention, the inducer housing includes an end wall which supports the cylindrical intake duct for axial movement. A set of circumferentially spaced and axially extending elongated bolts extend through an annular flange secured to the intake duct and are threaded into nuts secured to the housing end wall to provide for adjusting the intake duct axially to adjust the area of the nozzle opening. An annular sliding flange surrounds the intake duct adjacent the housing end wall and is engaged by nuts on the threaded bolts for clamping a resilient O-ring between the flange and the end wall to form a fluid-tight seal between the end wall and the intake duct.
Other features and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.